1. Field of the Invention
This invention relates to rotary displacement devices such as fluid pumps or motors. More particularly, this invention relates to improvements to the rotary fluid pump mechanism disclosed in U.S. Pat. No. 3,544,243.
2. Description of the Prior Art
U.S. Pat. No. 3,544,243 discloses a rotary fluid pump mechanism comprising a housing formed by a generally drum-shaped member having an end assembly secured across an open end thereof. A pump drive shaft is journalled within the housing to rotate a pump assembly therein. The pump assembly comprises a rotor assembly secured to the proximal end of the drive shaft. A hub structure is rotatably disposed within the rotor assembly by means of a rotor pin connected to the end assembly. The axis of rotation of the hub assembly is positioned eccentric to the axis of rotation of the rotor assembly. A plurality of vanes interconnect the rotor assembly and the hub assembly. The edges of the vanes seal against the bottom of the rotor assembly and against a wear plate connected to the end assembly in juxtaposition with the open end of the rotor assembly, thereby creating a plurality of pump chambers. An input port and an output port are connected to the end assembly and through the wear plate to be in fluid communication with the pump chambers as the pump chambers cyclically increase and decrease in volume, respectivley, as the rotor assembly and the hub assembly is rotated.
The patented pump as disclosed above has worked quite satisfactorily in a great multitude of applications and environments. Moreover, the operating life of the patented pump has been adequately long, and has been somewhat increased by manufacturing the pumps, particularly the vanes, from state-of-the-art materials. Unfortunately, there have been a number of problems associated with the patented pump which have rendered the pump unsuitable for use in some applications.
One problem associated with the patented pump has been a substantial amount of leakage between the drive shaft and the housing. This occurs primarily when the pump is operating at relatively high speeds. The most prevalent problem, however, has been excessive wearing of the vanes of the hub assembly during operation. After long operation, the edges of the vanes tend to become torn as they wrap about the rotor blocks of the hub assembly thereby preventing the vanes from forming an adequate seal against the bottom of the rotor assembly and against the wear plate. To repair the patented pump the entire pump assembly including the rotor assembly and the hub assembly must be replaced with a new pump mechanism. Accordingly, it is almost just as economical to replace the entire pump instead of rebuilding or repairing a used pump.
Therefore it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the fluid pumping art.
Another object of this invention is to provide a fluid pump including means for preventing leakage between the drive shaft and the housing of the pump when the pump is operating at relatively high speeds.
Another object of this invention is to provide a fluid pump having a replaceable rotor assembly to facilitate the rebuilding or repair of a worn pump.
Another object of this invention is to provide a fluid pump having specially contoured rotor blocks which substantially reduce the amount of wear of the vanes as the vanes wrap about the rotor block during operation of the pump.
Another object of this invention is to provide a fluid pump having an input port and an output port disposed through the wear plate to be in fluid communication with the pump chambers as the pump chambers cyclically increase and decrease in volume, respectively, during operation of the pump.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.